This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: When an insecticide application fails to control bluegreen aphid, application conditions may not be the only cause. Research has identified resistant populations across southern Australia, confirming that repeated reliance on broad-spectrum insecticides is no longer sustainable.
Bluegreen aphid (BGA) affects alfalfa, medic, clover and pulse crops through feeding damage and virus transmission. Populations can increase rapidly, completing a generation in around 10 days under favorable conditions. Following the first confirmation of insecticide resistance in BGA in 2021–22, research conducted from 2022 to 2025 investigated its distribution and potential alternative controls.
BGA populations were collected from pasture, pasture seed and pulse crops across South Australia, Victoria and southern New South Wales, particularly where control failures had been reported. Laboratory bioassays compared these populations with insecticide-susceptible BGA. The research identified another 21 populations resistant to one or more organophosphate, carbamate or synthetic pyrethroid insecticides.
Resistant populations were found from the Eyre Peninsula to near Tamworth and across several parts of Victoria. Resistance was particularly common in alfalfa but was also detected in lentil crops on the Yorke Peninsula and in Victoria's Wimmera and Mallee regions. Resistance to organophosphates and synthetic pyrethroids was generally more common and stronger than resistance to pirimicarb.
The project tested flupyradifurone, sulfoxaflor and flonicamid against resistant and susceptible BGA. No field-evolved resistance or cross-resistance to these active ingredients was detected, indicating that they may offer alternative control options. Registrations and permits differ between products and crops and may change.
Growers must check current Australian Pesticides and Veterinary Medicines Authority requirements and follow label directions before use. Researchers also identified 132 parasitoid wasps collected from 25 locations across South Australia, New South Wales and Victoria. Every specimen was Aphidius ervi, suggesting that natural control of BGA may depend heavily on this species.
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